ML110590568

McGuire Nuclear Station, Units 1 and 2, Request for Additional Information Regarding License Amendment Request Related to the Emergency Core Cooling System Initiative

ML110590568
Person / Time
Site:	Mcguire, McGuire
Issue date:	01/31/2011
From:	Thompson J H Plant Licensing Branch II
To:	Ashe K L Duke Energy Carolinas
Thompson Jon, NRR/DORL/LPL 2-1, 415-1119
References
Download: ML110590568 (2)

Text

From: Thompson, Jon Sent: Monday, January 31, 2011 2:09 PM To: Ashe, Ken Cc: Sallman, Ahsan; Dennig, Robert; Khanna, Meena; Basavaraju, Chakrapani

Subject:

Request for Additional Information Re: License Amendment Request dated May 28, 2010

SUBJECT:

MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 (MCGUIRE 1 AND 2), REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING LICENSE AMENDMENT REQUEST RELATED TO THE EMERGENCY CORE COOLING SYSTEM (ECCS) INITIATIVE (TAC NOS. ME4051 AND ME4052)

By letter dated May 28, 2010, as supplemented by letter dated November 15, 2010, Duke Energy Carolinas, LLC (the licensee), submitted a proposed license amendment to change the McGuire 1 and 2 Technical Specifications (TSs). The proposed change would revise the TSs to allow manual operation of the containment spray system and to change the setpoints for the refueling water storage tank at McGuire 1 and 2.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed document describes this RAI. A written response should be provided to the NRC staff for all these RAI questions by March 3, 2011, in order to support our timely review of this application. Please inform me as soon as possible if you are unable to support this response timeframe.

If you have any questions, please call me at 301-415-1345.

Sincerely, Jon Thompson, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369, 50-370

Enclosure:

As stated REQUEST FOR ADDITIONAL INFORMATION (RAI)

BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING LICENSE AMENDMENT REQUEST (LAR) RELATED TO IMPLEMENTATION OF THE EMERGENCY CORE COOLING SYSTEM (ECCS) WATER MANAGEMENT INITIATIVE MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 (MCGUIRE 1 and 2)

By letter dated May 28, 2010 (ADAMS Accession No. ML101600256), as supplemented by letter dated November 15, 2010 (ADAMS Accession No. ML103270051), Duke Energy Carolinas, LLC (Duke Energy or the licensee), submitted a license amendment request (LAR) for the McGuire Nuclear Station, Units 1 and 2. The proposed amendment would allow the manual operation of the containment spray system (CSS) in lieu of automatic operation, and revise the minimum volume and low level set point on the refueling water storage tank (RWST). One of the objectives of this LAR is to maximize the amount of water available for emergency core cooling from the RWST.

Based on our review of the license amendment request, the US Nuclear Regulatory Commission (NRC) staff has identified the following RAI questions, for which additional information is required, before the NRC staff can complete its review.

1. In Section 3.2.3 of Attachment 1 of the LAR, the licensee describes that the sump temperature at the time of switchover is approximately 197oF, which is above the previous design temperature of 190oF, and indicated that the piping and components affected by this increase in the sump temperature have been evaluated at a temperature of 200oF. The licensee is requested to provide a comparative summary of the results of the maximum piping stresses for the containment spray system (CSS), along with the allowable stress limits and the applicable code version for the reanalysis and design basis analysis.

2. In Section 3.2.3 of Attachment 1 of the LAR, the licensee describes that as a result of the revised loadings from the evaluation of the CSS pipe stress analysis, 13 pipe support restraints in the auxiliary building were re-qualified and 224 pipe supports in the reactor building will be requalified.

(a) The licensee is requested to clarify if the increased loadings on such a significant number of pipe supports are caused by the small increase in the sump temperature, only, or if any other effects contributed to the re-qualification of the supports.

(b) The licensee is also requested to complete the re-qualification of the affected pipe support restraints and provide a summary of the results of this analysis.

3. In Section 3.2.3 of Attachment 1 of the LAR, the licensee describes that the re-qualification of the reactor building pipe supports (approximately three pipe support restraints in the Unit 2 reactor building annulus, and one pipe support restraint in the Unit 1 reactor building annulus) potentially require modification and will be performed in accordance with the requirements of 10 CFR 50.59. It appears that the licensee has not definitively established the actual modifications for the pipe support restraints.

(a) While the installation of the modified supports can be done under 10 CFR 50.59, the licensee is requested to definitively identify the pipe support restraints requiring modification and complete the pipe support restraint re-qualification for those support restraints in support of this LAR.

(b) The licensee is also requested to provide a summary table of the support restraints requiring modification, including a brief description of the support restraint direction and type, and the required modification

4. Section 3.2.2 "NPSH Analysis", second paragraph, last sentence states: "The reanalysis results demonstrated that greater than two (2) feet of water head margin was afforded for the limiting available NPSH condition (i.e., one train of CS) above that required."

(a) What is the basis of the required NPSH that was used to compare with the available NPSH?

(b) What are the uncertainties included in evaluation of the required NPSH? (c) Outline all the conservatisms in the calculation of the limiting value of available NPSH.